Needle muscle biopsy.

We review our experience with needle muscle biopsy, including technique, results, complications, and outcome. We have collected data from 40 consecutive patients undergoing needle muscle biopsy of the quadriceps muscle. All biopsies were performed by the same operator and 98% were performed in the outpatient clinic. Specimens were sent to pathology for processing, staining, and interpretation. Follow-up clinical information was obtained by chart review. The ages of the patients ranged from 9 to 84 years, including three children. Of the 27 patients with a prebiopsy suspicion of idiopathic inflammatory myopathy (polymyositis, dermatomyositis, or inclusion body myositis) 13 had biopsies with consistent pathologic changes. Seven patients in this group had no pathologic diagnosis - none of these patients subsequently developed active myositis. Other conditions seen included mitochondrial myopathy, neuropathy, and type II fiber atrophy. Biopsies were very well tolerated, and no significant complications were seen. Therapeutic decisions were influenced most by needle muscle biopsy results obtained from patients suspected of having idiopathic inflammatory myopathy. Needle muscle biopsy charges were approximately 40% lower than those for open biopsies performed during the same interval. Needle muscle biopsy is a safe, care-effective, and cost-effective alternative to open muscle biopsy in the evaluation of a variety of myopathies.